NAME

DESCRIPTION

This document describes differences between the 5.13.4 release and the 5.13.5 release.

If you are upgrading from an earlier release such as 5.13.3, first read perl5134delta, which describes differences between 5.13.3 and 5.13.4.

Core Enhancements

Adjacent pairs of nextstate opcodes are now optimized away

Previously, in code such as

use constant DEBUG => 0;
sub GAK {
warn if DEBUG;
print "stuff\n";
}

the ops for warn if DEBUG; would be folded to a null op (ex-const), but the nextstate op would remain, resulting in a runtime op dispatch of nextstate, nextstate, ...

The execution of a sequence of nextstate ops is indistinguishable from just the last nextstate op so the peephole optimizer now eliminates the first of a pair of nextstate ops, except where the first carries a label, since labels must not be eliminated by the optimizer and label usage isn't conclusively known at compile time.

API function to parse statements

The parse_fullstmt function has been added to allow parsing of a single complete Perl statement. See perlapi for details.

API functions for accessing the runtime hinthash

A new C API for introspecting the hinthash %^H at runtime has been added. See cop_hints_2hv, cop_hints_fetchpvn, cop_hints_fetchpvs, cop_hints_fetchsv, and hv_copy_hints_hv in perlapi for details.

C interface to caller()

The caller_cx function has been added as an XSUB-writer's equivalent of caller(). See perlapi for details.

Incompatible Changes

Magic variables outside the main package

In previous versions of Perl, magic variables like $!, %SIG, etc. would 'leak' into other packages. So %foo::SIG could be used to access signals, ${"foo::!"} (with strict mode off) to access C's errno, etc.

This was a bug, or an 'unintentional' feature, which caused various ill effects, such as signal handlers being wiped when modules were loaded, etc.

This has been fixed (or the feature has been removed, depending on how you see it).

Changes to Existing Diagnostics

Utility Changes

The use of a deprecated goto construct has been removed [perl #74404].

Testing

The new t/lib/universal.t script tests the Internal::* functions and other things in universal.c.

A rare race condition in t/op/while_readdir.t has been fixed, stopping it from failing randomly when running tests in parallel.

The new t/op/leaky-magic.t script tests that magic applied to variables in the main packages does not affect other packages.

Platform Support

Platform-Specific Notes

VMS

Make PerlIOUnix_open honour default permissions on VMS.

When perlio became the default and unixio became the default bottom layer, the most common path for creating files from Perl became PerlIOUnix_open, which has always explicitly used 0666 as the permission mask.

To avoid this, 0777 is now passed as the permissions to open(). In the VMS CRTL, 0777 has a special meaning over and above intersecting with the current umask; specifically, it allows Unix syscalls to preserve native default permissions.

Internal Changes

CALL_FPTR and CPERLscope have been deprecated.

Those are left from an old implementation of MULTIPLICITY using C++ objects, which was removed in Perl 5.8. Nowadays these macros do exactly nothing, so they shouldn't be used anymore.

For compatibility, they are still defined for external XS code. Only extensions defining PERL_CORE must be updated now.

lex_stuff_pvs() has been added as a convenience macro wrapping lex_stuff_pvn() for literal strings.

The recursive part of the peephole optimizer is now hookable.

In addition to PL_peepp, for hooking into the toplevel peephole optimizer, a PL_rpeepp is now available to hook into the optimizer recursing into side-chains of the optree.

Selected Bug Fixes

A regression introduced in Perl 5.12.0, making my $x = 3; $x = length(undef) result in $x set to 3 has been fixed. $x will now be undef.

A fatal error in regular expressions when processing UTF-8 data has been fixed [perl #75680].

An erroneous regular expression engine optimization that caused regex verbs like *COMMIT to sometimes be ignored has been removed.

Opening a glob reference via open $fh, ">", \*glob will no longer cause the glob to be corrupted when the filehandle is printed to. This would cause perl to crash whenever the glob's contents were accessed [perl #77492].

The postincrement and postdecrement operators, ++ and --, used to cause leaks when being used on references. This has now been fixed.

A bug when replacing the glob of a loop variable within the loop has been fixed [perl #21469]. This means the following code will no longer crash:

for $x (...) {
*x = *y;
}

Perl would segfault if the undocumented Internals functions that used reference prototypes were called with the &foo() syntax, e.g. &Internals::SvREADONLY(undef)[perl #77776].

These functions now call SvROK on their arguments before dereferencing them with SvRV, and we test for this case in t/lib/universal.t.

When assigning a list with duplicated keys to a hash, the assignment used to return garbage and/or freed values:

An earlier release of the 5.13 series of Perl changed the semantics of opening a reference to a copy of a glob:

my $var = *STDOUT;
open my $fh, '>', \$var;

This was a mistake, and the previous behaviour from Perl 5.10 and 5.12, which is to treat \$var as a scalar reference, has now been restored.

The regular expression bracketed character class [\8\9] was effectively the same as [89\000], incorrectly matching a NULL character. It also gave incorrect warnings that the 8 and 9 were ignored. Now [\8\9] is the same as [89] and gives legitimate warnings that \8 and \9 are unrecognized escape sequences, passed-through.

Known Problems

The upgrade to Encode-2.40 has caused some tests in the libwww-perl distribution on CPAN to fail. (Specifically, base/message-charset.t tests 33-36 in version 5.836 of that distribution now fail.)

The upgrade to ExtUtils-MakeMaker-6.57_05 has caused some tests in the Module-Install distribution on CPAN to fail. (Specifically, 02_mymeta.t tests 5 and 21, 18_all_from.t tests 6 and 15, 19_authors.t tests 5, 13, 21 and 29, and 20_authors_with_special_characters.t tests 6, 15 and 23 in version 1.00 of that distribution now fail.)

Acknowledgements

Perl 5.13.5 represents approximately one month of development since Perl 5.13.4 and contains 74558 lines of changes across 549 files from 45 authors and committers:

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

Reporting Bugs

If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup and the perl bug database at http://rt.perl.org/perlbug/ . There may also be information at http://www.perl.org/ , the Perl Home Page.

If you believe you have an unreported bug, please run the perlbug program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of perl -V, will be sent off to perlbug@perl.org to be analysed by the Perl porting team.

If the bug you are reporting has security implications, which make it inappropriate to send to a publicly archived mailing list, then please send it to perl5-security-report@perl.org. This points to a closed subscription unarchived mailing list, which includes all the core committers, who be able to help assess the impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the problem across all platforms on which Perl is supported. Please only use this address for security issues in the Perl core, not for modules independently distributed on CPAN.

SEE ALSO

The Changes file for an explanation of how to view exhaustive details on what changed.

The INSTALL file for how to build Perl.

The README file for general stuff.

The Artistic and Copying files for copyright information.

Module Install Instructions

To install perl5135delta, simply copy and paste either of the commands in to your terminal